The Pollitt X4 (GCR Class 13) 4-2-2 Singles

"Singles", locomotives with single driving axles, were a popular design for express passenger locomotives
during the middle of the 19th Century. As train loads grew, they went out of fashion, but had a brief
renaissance after steam sanding gear appeared in 1886. This renaissance ended around 1900 as
train loads continued to grow, and virtually all had been withdrawn before Grouping in 1923.
The only 4-2-2s to survive were the six X4s designed by
Pollitt for the Great Central Railway (GCR).

The X4s (GCR Class 13) were the last locomotive type to be designed by
Pollitt before his retirement. Indeed, only
two had been built when
Robinson took over.
Introduced in 1900, the X4s were also the last of the 4-2-2 Singles.
Robinson quickly cut the order from
ten down to six, so he was probably well aware the 4-2-2 design was in decline.

The X4 design had a lot in common with
Pollitt's
D6.
He also added a large grate of almost 25sq ft., and used a high boiler pressure of 200psi.
The boiler pressure was quickly reduced to 160psi due to problems with slipping.

In 1911, Robinson rebuilt No. 969
with a larger boiler, but this was removed when a superheater was fitted in 1915.
Between 1915 and 1919, four of the class (Nos. 967, 969, 970, and 972) had superheaters fitted.
Nos. 968 and 971 kept their saturated boilers.

Originally built for the GCR's London Extension, they only worked this line until 1903 when they
were replaced by
RobinsonD9s.
All six locomotives were then moved to Cheshire, where they allocated for the rest of the lives.
Despite some slipping problems, the X4s proved capable of handling the Cheshire express trains.
Although all six survived into LNER ownership, they were of an outdated design and
the LNER started withdrawals in December 1923. The last locomotive was withdrawn in 1927.
The four superheated boilers were found to be in good condition, and these were kept as stationary
boilers.

Technical Details

These details describe the superheated X4s at Grouping in 1923.

Cylinders (x2):

19.5x26in.

Motion:

Stephenson

Piston Valves:

8.75in. diameter

Boiler:

Max. Diameter:

4ft 3in

Pressure:

160psi

Heating Surface:

Total:

1043 sq.ft.

Firebox:

128 sq.ft.

Superheater:

138 sq.ft.

Tubes:

490 sq.ft. (86x 1.875in)

Flues:

287 sq.ft. (18x 5.25in)

Grate Area:

24.8 sq.ft.

Wheels:

Leading:

3ft 6in

Coupled:

7ft 9in

Trailing:

4ft 6in

Tender:

4ft 3in

Tractive Effort:

14,457lb

(@ 85% boiler pressure)

Length:

54ft 9.25in

Wheelbase:

Total

45ft 5in

Engine:

22ft 11in

Tender:

13ft 0in

Weight (full):

Total:

92 tons 17cwt

Engine:

49 tons 17cwt

Tender:

43 tons 0cwt

Max. Axle Load:

18 tons 10cwt

Preservation

The last X4 (No. 5927) was withdrawn in 1927. Although it took part in the Stockton & Darlington celebrations
in 1925, it was not kept for preservation.